The present invention relates to an apparatus for crushing stumps and other felling waste into chips.
Owing to an increasing shortage of wood fibre raw material in forests in relation to the increasing demand in the world, the wood countries have for the last years tried to utilize a greater part of the tree than had earlier been the case. In this respect the attention has particularly been directed to the tree stumps, mainly since the stumps and also the roots give an essential wood fibre addition of high pulp quality. A number of devices for stump removal (stump extraction) have been developed. In connection with or after the removal of the stump out of the ground a first dividing of the stump is carried out in order to make it together with its root system more readily workable.
The divided stumps have up to now been transported on a cross-country transport vehicle to a central location adjacent a road, from which location the further transport up to cellulose factories has been made by motor lorries or trucks. In the cullulose factories the stumps have been treated in different ways in order to remove earth and stones prior to the machining into chips. Above all two disadvantages, however, exist by such a transport and chipping. One disadvantage is that the stump portions with their projecting roots do not give a solid mass percentage that is sufficiently profitable for the load volume of the transport vehicles. The second disadvantage is the relatively large quantity of earth and stones in the irregularities and projections of the stumps. Also ingrown stones exist. The cellulose factories only allow a small part of these impurities to be present on the stumps upon delivery to the factory.